Carbon Pastes and Carbon Paste Electrodes - Electroanalysis with Carbon Paste Electrodes - page 38

A B C D

FIGURE 2.9 Four.variants.of.carbon.paste.electrodes.used.in.Adams's.laboratories..(A).Shielded.CPE.in.
Telon;.(B).planar.CPE.with.ground.glass.itting;.(C).rotated.disc.CPE;.(D).planar.CPE..(A.photo.from.Prof..
Kuwana's.personal.archives;.presented.with.his.kind.permission.)

2.3.1.1 Rotated Disc Electrodes for Hydrodynamic Measurements
Yet. before. going. to. such. more. lexible. CPE-holders. and. in. accordance. with. chronological. order,.
it. is. necessary. to. present. rotated/rotating. variants. of. carbon. paste-illed. electrode. bodies. (plugs,.
cylindrical.rods.with.drilled.end.holes,.etc.).that.had.belonged.to.a.regular.equipment.of.electro-
chemists. in. the. early. era. of. carbon. paste. [2,3,10,18,528-530].. (Two. basic. variants. of. RD-CPEs.
are. also. included. in. Figures. 2.8. and. 2.9. as. documented. in. both. legends.). However,. the. respec-
tive.constructions.had.been.of.interest.not.only.in.theoretically.oriented.studies.of.electrode.reac-
tions,.but.could.also.be.highly.effective.in.contemporary.electroanalysis.[530],.as.well.as.later.on.
[63,249,519,531-535]..In.the.meantime,.the.respective.designs.underwent.slight.variations—from.
common.cylindrical.[10,528].to.bell-shaped.variants.[12,18],.via.unshielded.and.shielded.modiica-
tions.[3,11],.up.to.special.rotated.assemblies.that.have.been.described.and.used.recently.[536,537],.
including.studies.with.new.carbon.paste.mixtures.made.of.CNTs.and.(RT)ILs.[127].
A.rather.unique.variant.of.rotated.electrode.was.the.so-called. rotating ring-disc carbon paste
electrode ,. RRD-CPE .(see.again.Figures.2.8.and.2.9.and.the.Scheme/Design.“C”).devised.and.suc-
cessfully.used.for.studying.some.multistep.electrode.mechanisms.[10,11]..Its.dual.working.surface.
allowed.one.to.apply.different.potentials.at.both.ring.and.disc.parts.separately,.thereby.even.paral-
lel.or.consecutive.electrode.processes.could.be.registered.one.after.the.other.and.without.mutual.
interferences.

2.3.2 p isTon -d riVen e leCTrode h olders
Apparently.the.most.elegant.way.of.how.to.renew.the.used.carbon.paste.was.introduced.by.Monien.
et.al..[31].who.had.smartly.utilized.the.principle.of.a.micrometric.screw.for.quick.and.very.effec-
tive.extrusion.of.the.paste.out.of.the.body..As.seen.in.Figure.2.8.(Scheme.“D”),.the.cavity.inside.a.
glass.body.with.a.Telon.sleeve.was.formed.by.the.respective.position.of.the.screw.and,.reportedly,.
could. contain. up. to. 3.5.g. carbon. paste.. The. paste. pulled. out. of. the. holder. could. then. be. simply.
cut.off.and.polished.by.a.soft.paper.tissue—for.example,.wet.ilter.paper.is.also.very.convenient.
[175]—the.entire.operation.lasting.a.few.seconds.only..In.fact,.Monien's.design.was.the.predecessor.
of.piston-driven.constructions.that.came.to.the.fore.soon.after.[33],.supplemented.yet.with.a.special.
tool.for.cutting.the.extruded.paste.with.a.stretched.piano.string.[33,538]..Later.constructions.had.
also.combined.the.material.used,.which.was.the.case.of.a.CPE.consisting.of.a.glass.body.and.plastic.
piston.[539].
Laboratory-made.carbon.paste.holders.with.piston.had.been.of.continuing.interest.and.the.real-
ized.constructions.brought.numerous.innovations,.offering.useful.and,.in.some.cases,.completely.
new.construction.details.